ABSTRACT
The osmotic relations between white and yolk in the fertilised and unfertilised hen’s egg have often been investigated. The complexity of these relations is presumably due largely to peculiar physico-chemical properties of the colloid constituents of the egg. The purpose of this paper is primarily to confirm the existence of a considerable osmotic difference between white and yolk in the unfertilised hen’s egg, in reply to a recent denial, and then to describe some preliminary experiments on the state of water and of several dissolved substances in the egg. The bearing of these experiments on the relations between white and yolk in the intact egg will then be discussed briefly.
Throughout this paper vapour-pressure differences are given as the strength of a sodium chloride solution, expressed in gm. NaCl dissolved in 100 gm. water, which would produce the same galvanometer deflection when opposed on the vapour-pressure thermopiles by distilled water. The units used are thus immediately related to what is actually measured, since the thermopiles are always calibrated with a known sodium chloride solution. This seems preferable to the common habit of converting the quantity measured into “absolute “or “ideal” units such as osmolality, ideal molality, etc. In later tables “freezing-point depressions” are calculated from the vapour-pressure data simply for convenience in comparing the data with freezing-point determinations of other workers, but it should be remembered that the vapour pressure of a substance at 180 C. does not necessarily have any “ideal” or thermodynamic connection with the temperature at which the substance freezes. This is especially true of the complex materials dealt with here(cp.p.327 and Fig. 1).
